Generally, a snow chain is a representative example of a device for preventing slipping of a vehicle. The snow chain is attached to a tire of the vehicle to prevent slipping of the vehicle when traveling on icy roads attributable to snow. On a road, such as a highway, snow chains cannot be used because they cause damage to the road and thus increase accident risk. In this case, typically, special tires, such as snow tires or studded tires, for preventing slipping of a vehicle are used.
Meanwhile, in the case of an integrated vehicle slipping prevention device, it is difficult for a woman, weak or handicapped user to attach or detach the device to a tire of a wheel. In addition, when a user abruptly meets a snowy or icy road, it is not easy to rapidly attach the device to a tire. Moreover, because forward or backward movement of the vehicle is required to attach or detach the device to or from the tire, work of attaching or detaching the device to or from the tire on a sloping road is very difficult.
Furthermore, the integrated vehicle slipping prevention device is typically designed to have a structure suitable for a tire of a passenger vehicle. In the case of a large bus or truck to carry a lot of passengers or freight, each of the rear wheels which are drive wheels is made in a form of a double wheel (the double wheel is used to reduce a risk of a flat accident in such a way as to reduce a load applied to each tire). Thus, it is difficult to apply the integrated vehicle slipping prevention device to a large vehicle which is typically provided with double wheels.
Furthermore, in the integrated vehicle slipping prevention device, it is very inconvenient to attach or detach the chain to or from the tire. In consideration of a relatively narrow width and small diameter of a double wheel tire used in a freight transportation vehicle, if the integrated vehicle slipping prevention device designed for passenger vehicles is attached to a tire of a truck or bus, force with which the device is attached to and is brought into contact with the tire may be unsatisfactory. Thus, it may be impossible to effectively transmit driving force or to provide sufficient braking force.
In order to overcome the above-mentioned problems, a vehicle slipping prevention device was proposed, in which chains are attached to tires of a double wheel belonging to rear wheels of a large vehicle, the chains passing through centers (wheel) of the tires. However, this vehicle slipping prevention device has the following several problems.
In this conventional vehicle slipping prevention device, the snow chains are attached to the circumferential outer surfaces of the tires while passing through the wheel to which the tires are mounted. The snow chains are rotated along with the tires. Here, when braking force is continuously transmitted to the tires which rotate at a high speed, the snow chains may not be able to maintain intervals therebetween and may be focused in one direction. Thus, braking force cannot be evenly transmitted to the entire area of the double wheel. In addition, a load is focused on the snow chains, so that the chains are damaged or removed from the tires.
Furthermore, in the conventional vehicle slipping prevention device, when the vehicle travels, an excessive load may be focused on the device, so that coupling portions of the snow chains may be undesirably loosened, with the result that the braking force is abruptly removed and the possibility of a large accident is increased. In other words, the conventional vehicle slipping prevention device has a problem of low safety.
As well, the conventional vehicle slipping prevention device is configured such that a plurality of spikes is directly attached to the double wheel without having a separate interval maintenance means. When the vehicle travels on an uneven road surface, the snow chains may be undesirably gathered at one side and entangled so that the vehicle may not be steered in the direction in which the driver steers the vehicle, for example, the braking force may be applied in a direction in which the centrifugal force is applied when the vehicle suddenly turns, thus causing an accident.
In an effort to overcome the above-mentioned problems experienced with the conventional vehicle slipping prevention device, a vehicle slipping prevention device was proposed in Korean Patent Registration No. 10-0526439 (date: Oct. 28, 2005) which was filed by the applicant of the present invention and entitled “DEVICE FOR PREVENTING SLIPPING OF VEHICLE”. In this technique, the device is attached to tires of a double wheel belonging to rear wheels of a large vehicle in such a way that slipping prevention spikes which are coupled to each other by a chain and arranged at regular intervals are inserted between the tires of the double wheel. As well, a vehicle slipping prevention device for improving the device of No. 10-0526439 was proposed in Korean Patent Application No. 10-2007-23109, which was filed by the applicant of the present invention and entitled “DEVICE FOR PREVENTING SLIPPING OF VEHICLE”.
FIGS. 1 through 6 illustrate one representative example of the conventional vehicle slipping prevention devices.
As shown in the drawings, the conventional vehicle slipping prevention device includes a plurality of spikes 1, a connection member 2, and a fastener 5.
Each spike 1 has on a medial portion thereof an insert part 1a which is bent in a V shape such that the insert part 1a is inserted into a space between tires of a double wheel 200, and close contact parts 1c which are integrally extend from the respective opposite ends of the insert part 1a and are flush with each other to be brought into close contact with surfaces of the respective tires. A bent portion R is formed on a junction between the insert part 1a and each close contact part 1c. Several rigid protrusions 1b are integrally formed on the each close contact part 1c. 
The connection member 2 couples the insert parts 1a of the spikes 1 to each other.
The fastener 5 includes a catch 3, which has on a first end thereof a connection end 3a which is coupled to a first end of the connection member 2. The catch 3 further has an insert end 3b on a second end thereof opposite the connection end 3a. Locking holes 3c are formed in the catch 3 between the connection end 3a and the insert end 3b and are arranged in a row. The fastener 5 further includes a clamp 4, which has a clamp body 4g, a support pin 4c, a rotating pin 4e, a tension spring 4h and a clamping member 4k. The clamp body 4g has a ‘U’ shape such that the insert end 3b of the catch 3 is inserted thereinto. In detail, a connection end 4a is formed on one end of a bottom plate 4b of the clamp body 4g, so that a second end of the connection member 2 is connected to the connection end 4a. Sidewall plates 4g′ are provided on respective opposite edges of the bottom plate 4b. Support pin holes 4d, into which the support pin 4c is fitted, and rotating pin holes 4f, into which the rotating pin 4e is fitted, are sequentially formed through the sidewall plates 4g′ based on the connection end 4a. The clamping member 4k has a locking piece 4j which is fastened to the upper part of the rotating pin 4e, and a locking end 4i which protrudes downwards from the locking piece 4j and is hooked to one of the locking holes 3c. In addition, the clamping member 4k is connected to and supported by the tension spring 4h, which is connected to the support pin 4c, so that the clamping member 4k is rotatable around the rotating pin 4e and is returnable to its original state using the tension spring 4h. 
To attach the conventional vehicle slipping prevention device to the double wheel 200, the vehicle is stopped, and the device is disposed between the tires of the double wheel 200.
Thereafter, the vehicle slipping prevention device is wound around the circumferences of the tires of the double wheel 200, and the insert end 3b of the catch 3 is inserted into the clamp 4. Then, the locking piece 4j of the clamping member 4k is inserted into and locked to one of the locking holes 3c of the catch 3, thus completing the attachment of the vehicle slipping prevention device to the double wheel 200.
Here, the catch 3 which passes through the clamp 4 is exposed above the connection member 2.
However, in the conventional vehicle slipping prevention device, because the insert end 3b and the bent portions R of the close contact parts 1c are angled, stress is concentrated to the angled portions by impact generated when the close contact parts 1c come into contact with the road surface while the vehicle travels. Thereby, fatigue fracture may be induced.
Furthermore, when abrasion of the tires of the double wheel 200 is minimal, a length to which the insert end 3b of the catch 3 is exposed from the clamp 4 is relatively short. However, if the diameters of the tires of the double wheel 200 are reduced by abrasion, a length to which the insert end 3b of the catch 3 is exposed from the clamp 4 is increased.
As such, in the case where a length to which the insert end 3b of the catch 3 is exposed from the clamp 4 is increased, the conventional vehicle slipping prevention device is problematic in that the catch may be brought into contact with the road surface by centrifugal force generated when the vehicle travels, because the catch which passes through the clamp 4 is disposed outside the connection member 2.
In addition, when the catch 3 which is exposed outside the tires of the double wheel 200 is continuously struck to the road surface, impacts are continuously applied to the catch 3, so that the catch 3 may be broken by the fatigue load.
Moreover, a broken piece of the catch 3 may be sprung out by centrifugal force, with the result that it may damage the vehicle body or tear the tires of the double wheel 200. As well, the broken piece may strike another vehicle which is traveling on an adjacent lane.
Furthermore, in the conventional vehicle slipping prevention device, if the portion at which the catch 3 is locked to the clamp 4 is damaged, the lock of the device may be loosened. If the loosened device is undesirably wound around the shaft of the double wheel or another wheel, a large accident may be caused.
As well, the conventional vehicle slipping prevention device is problematic in that the catch 3 which has been locked to the clamp 4 may be undesirably unlocked and removed from the clamp 4 by vibration and centrifugal force.
Because of the above problems, an improved vehicle slipping prevention device having a stable structure is required, in which a catch can be fundamentally prevented from being exposed outside a connection member and thus prevented from coming into contact with a road surface, and the catch can be prevented from being loosened or unlocked from a clamp by vibration and centrifugal force.